The invention relates to catalytic hydroconversion of coal to liquid and gaseous products, and more particularly to a supported catalyst for this process including bimodal pore distribution.
A number of processes have been described in the literature relating to the hydroconversion of pulverized coal to coal liquid in the presence of molecular hydrogen and a catalyst in a catalytic reactor. In one process, coal conversion involves slurrifying solid pulverized coal in a solvent which is directed through a reactor with the hydrogen gas stream under high pressure and temperature. After conversion, the slurry product is collected. One such process, referred to as the H-Coal process, by Hydrocarbon Research, Inc., is performed in an ebullated catalyst fixed tubular reactor in which the catalyst and coal slurry are suspended and mixed.
The catalyst employed in the above processes include a variety of catalytically active substances deposited on porous support particles having large surface area. As set out in the background of U.S. Pat. No. 3,635,814, previous investigators have indicated that the pore size for a catalyst is on the order of 50 to 250 angstroms with the most frequent pore size being 60 angstroms. Many of such catalysts are of unimodal distribution, that is, including only one major distribution peak of average diameters of pore volume. On the other hand, there is a product on the market designated HDS-1442A by American Cyanamid Corporation with bimodal pore distribution having a major peak of smaller pore volume distribution (below 600 angstroms) and a second major peak pore volume distribution above 1,000 angstroms.
One problem with coal liquefaction catalysts is that they tend to deactivate during use as by clogging of the pores. This limits the effective life of the catalyst prior to regeneration.